Microscale systems that contain integrated structural and functional microscale components such as pumps, valves, channels, and sensors are highly desirable in microfluidics applications, including chemical and fermentation stream monitoring, physiologic analyte monitoring, drug delivery, and lab-on-a-chip applications. Microscale components result in reduced sample and waste volumes, features that are particularly useful when sample availability, sample expense, waste disposal costs, or safety are a concern. Incorporation of microscale components into analyte-sensing devices can facilitate the detection of multiple analytes from a single small sample. Highly integrated systems can allow a controlled response to a particular analyte, for example, by coupling the delivery of a particular compound with the detection of the analyte. Such systems have wide applicability across the environmental, chemical, medical, and biotechnological fields.
Current manufacturing and assembly methods for microscale systems rely on scaled-down versions of macroscale processes, resulting in limited flexibility of design, high cost, and long development times. For example, the micron-range size of the components makes handling difficult; electrostatic, surface, and other physical forces can become dominant, thereby impeding effective manipulation of the components. Integration of multiple microscale components into a single device can represent a further challenge.
Active microscale valves are desirable components in microscale devices and systems. Conventional active microvalves couple a flexible diaphragm or membrane to an actuator that deflects the diaphragm or membrane in response to temperature or electromagnetic fields. Unfortunately, at the small sizes used in microscale devices, these valves may require undesirably high power consumption. It would be useful to reduce the power consumption required in microscale devices yet retain the active microvalve functionality. It would also be useful to have methods and devices that incorporate active microvalves in controlled drug delivery applications.